Wikipedia

Snake pipefish

Entelurus aequoreus, the Snake pipefish, is a species of pipefish native to the northeastern Atlantic Ocean where they are generally found amongst algae close in to shore. This species grows to a length of 60 centimetres (24 in) TL for females and 40 centimetres (16 in) TL for males with most individuals reaching a length of about 45 centimetres (18 in) TL for females and 32 centimetres (13 in) TL for males. This species is the only known member of its genus. This species is a popular denizen of public aquariums.